Whether or not you agree with the use of the term “Advanced Persistent Threat” (APT), we can agree that there is a very real threat from advanced intrusions which persist undetected in our systems.

By definition, these intrusions are advanced so our traditional (and increasingly ineffective) protection mechanisms such as firewalls and antivirus don’t catch these APTs.

Think of the APT as a “needle in the haystack” that we need to find. To make things worse, we aren’t sure what the needle looks like (no signatures). So how do we find them?

The answer may seem counterintuitive and is rooted in a whitelisting paradigm: Remove the hay that you know is good (“high assurance hay”). When you are done, the needles remain.You don’t have to know what needles (APTs) look like, you only need to know what high assurance hay looks like.

This simple analogy illustrates the foundational importance of “whitelisting” based approaches in information security across the entire stack — whether it is session flows on the network, applications that a system is allowed to execute or transactions on the back-end.

Of course, this example assumes you know what high assurance hay looks like. In the application control / whitelisting space that I research there are a number of providers that are stepping up to build high assurance databases of application executables including Bit9, CA, CoreTrace, Harris (acquired SignaCert), Lumension, McAfee, Symantec, Trend and others.

There is no silver bullet in information security, but applying a whitelisting-based mentality to all of our information security solutions should be foundational to keep the bad guys from gaining the upper hand – and to keep the needles out of our hay.

Thoughts on Advanced Persistent Threats: Finding the Needle in a Haystack

Very concise analogy that distills the whitelisting paradigm cleanly – I like it. I tend to think about the “haystack” from two different angles – I need to find the needles already in it (because they are definitely there and I want to remove them) and I also want to avoid having any new needles added moving forward. Do you think focusing on the “high assurance hay” solves both of these issues?

Also, there are lots of ways that whitelisting can make blacklisting approaches more effecient and effective.

High assurance workloads (desktop or server) are foundational, but if the workload directly supports end-users that are able to download, install and execute arbitrary code then blacklisting approaches will continue to be needed.

At Symantec, we see very few enterprises successfully implementing pure white listing. End-users really resist having one blanket policy of allowable white-listed applications. The CFO or CEO may not care that much (since they don’t tend to use edgier applications) but the software development and marketing teams often resent the policy. Bottom line, one policy with one approved whitelist of applications is now highly unpopular at most enterprises.

They key is to identify the volumes of applications that are in the wild and assign reputation scores to them. If an application is incredibly rare and unknown (relative to a comprehensive knowledge of known-good software now in circulation) it would be scored accordingly to help enterprises rate and rank the risks.

This approach is better at finding APTs, and enterprises don’t resist this kind of policy because it is adjustable. You can assign a reputation response threshold dependent upon the user that varies with their job function. For example, give the CFO a very constraining threshold of reputation so that very few applications of any kind of level of edgy risk ever reach his/her desktop, and give your software devs more permission to do the edgy things they need to do.

Agree partially. Your point about a pure whitelisting approach for end-user desktops is accurate. However, this is why my Gartner research refers to this as “Application Control” and not “whitelisting”. There are many shades of grey in the real world between things that we have a high assurance are good (whitelist) and those that we have a high assurance are bad (blacklist).

So, reputation services will be a key enabler to making application control work in the enterprise for end-users. Bit9, Symantec, Trend, McAfee and others are ALL building reputation databases.

On the other hand, servers and embedded devices are great candidates for a “pure” whitelisting / application control approach.

Ideally vendors would provide a foundational whitelist of high assurance applications and supplment this with the reputation database. Think of this as a continuum — for example, a score of a +10 if the application is known, digitially signed and received directly from the vendor. A score of -10 if the applicaiton is known to be malware… and everywhere in between for those shades of grey.

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